As an example of this type of paper feed device, there is a device including a paper stacking shelf on which a paper bundle is to be stacked, a paper transport belt that is disposed above the paper stacking shelf, and a fan that sucks air through air through holes of the paper transport belt, wherein an uppermost sheet of paper in the paper bundle is transported while being caused to adhere to the paper transport belt by sucking air through the air through holes of the paper transport belt.
Furthermore, in such a paper feed device, in order to stabilize the operation that causes an uppermost sheet of paper in the paper bundle to adhere to the paper transport belt, it is necessary to position the uppermost sheet of paper in the paper bundle at a proper height. Accordingly, a trailing edge portion (a paper edge portion that is oriented in a direction opposite to the paper transport direction) of paper in the paper bundle is pressed down so as to prevent the trailing edge portion of paper from moving upward, and a sensor that detects whether or not the upper face of the paper bundle is at a proper height is provided so the paper stacking shelf is lifted until it is detected that the upper face of the paper bundle has reached the proper height, for example.
For example, a paper feed tray device of Patent Document 1 includes a regulating member that regulates the position of a trailing edge of a paper bundle by being brought into contact with the trailing edge of the paper bundle, and a paper pressing lever that is supported in a rotatable manner on the regulating member, wherein, in a state in which the regulating member is in contact with the trailing edge of the paper bundle, the paper pressing lever is rotated to be brought into contact with a trailing edge portion of an upper face of the paper bundle, so that the trailing edge portion of paper in the paper bundle is prevented from moving upward. Furthermore, a sensor that detects that the paper pressing lever has reached a predetermined rotational position where the upper face of the paper bundle reaches the proper height is provided, and a tray is lifted until the upper face of the paper bundle pushes up the tip end of the paper pressing lever and the sensor detects the paper pressing lever at the predetermined rotational position. Furthermore, when the tray is lowered to the lower limit position, the tray is brought into contact with a tray detection lever and depresses the tray detection lever, a wire connecting the tray detection lever and the paper pressing lever is pulled down, so that the paper pressing lever is rotated to be withdrawn from the upper face of the paper bundle.    [Patent Document 1] JP H3-284546A